1. Field of the Invention
This invention relates to a clamping assembly for clamping a block of wearable material.
2. Prior Art
Blocks of wearable but wear-resisting material, for example reinforced phenolic resin, are utilized in sliding engagement with band saw blades or other moving metal parts, the blocks of wearable material acting as guides for maintaining alignment of the moving metal part for accurate cutting or the like. Conventionally, the block of wearable material is maintained in a holding means against a datum surface to maintain proper alignment of the block, and as the block wears adjustment means are provided to accomodate the wear. Some early holding and adjustment means had screws to advance the block towards the saw, after advancement the wear face of the block being "dressed" to provide an accurate wear face. This was time consuming and resulted in excessive saw "down time" as the saw could not operate whilst the blocks were being dressed or adjusted. A "quick change" saw guide assembly was developed which reduced saw down time appreciably by providing a quickly releasable holding structure which can be fitted to the saw with one nut and bolt or other means and yet holds a wear block accurately in a required position with no further adjustment being required until the block was worn beyond predetermined limits. The assembly was then removed and another block and holding structure substituted whilst the worn block was adjusted and re-faced for replacement. One type of quick change saw guide assembly has an upper clamping piece disposed oppositely to the datum surface, both of which overlap a substantial portion of the wearable block. Sometimes more than fifty percent of the volume of the block is necessarily located between opposed holding surfaces of the holding means and thus is unavailable for consumption by wear against the band saw blade or other moving metal element. This means that as the block wears down towards the block portion located between the opposed holding surfaces, eventually a point is reached where perhaps something of the order of fifty percent or more of the block remains intact, at which point no further consumption of the block is possible and it must thereafter be discarded and replaced by a fresh block. This results in considerable waste of the wearable material, which is often fairly costly.